Output devices, such as user devices for receiving broadcasts, decoding the broadcast, and outputting media content, such as video and/or audio content are in widespread use. One such example is a set-top-box (STB) used to receive broadcast television programmes, decode the broadcast and output programming to a display device.
Typically, output devices such as STBs consist of one or more silicon chips, other hardware components, and software from one or more sources. Key technologies destined for the STB are designed and/or manufactured by a first company and incorporated into silicon chips by a second company. These silicon chips are then provided to a third company, such as a STB manufacturer, who then assembles these and other software and/or hardware components into a STB. The STB may then be provided to a network operator who provides content to an end user for distribution e.g. on a subscription basis, or sold to an end user for the purpose of receiving content from a network operator. In this way, the silicon chip, and hence the STB, may have dormant functionality that is only activated under the control of the first company.
STBs, or components of them, can be programmed or configured to offer certain technologies or functionality to the STB manufacturer. For example, a component, when inserted into a STB by a STB manufacturer, may endow the STB with the capability of applying copy protection to received content such that subsequent video content output by the STB cannot be copied by a recording device. The first company may charge the third company and/or the network operator a licence fee to use the functionality, such as the copy protection functionality. Unfortunately, it is not uncommon for an unscrupulous party to attempt to circumvent the licence fee and provide the additional functionality in their set top boxes and/or networks.
In order to enforce the licence fee it is advantageous to be able to prove that the signal output by a STB, is associated with a particular party, such as a particular network operator or STB manufacturer.